Multiple waveguides may be used in certain optical transmission means, such as multi-core fibers. Multi-core fibers comprise several cores within the fiber with each core being able to transmit an optical signal. It is expected that multi-core fibers will play a major role in the newly developing field of Silicon Photonics. As used herein, “Silicon Photonics” means using a chip such as an integrated circuit (IC) having the ability for receiving optical signals along with the electronic functionality in the chip, for example a chip with silicon or III/V-materials. The advantages of Silicon Photonics are reduced space and power requirements concurrent with increased speed and lower costs. These photonic structures on an optical chip still have to be optically connected to the outer devices through optical waveguides such as optical fibers.
The geometry of the multi-core fibers makes them highly favorable for use in Silicon Photonics, since in a small volume the signals of multiple sources can be coupled to a single fiber. Especially edge coupling of a fiber to a silicon chip is very promising. Multi-core fibers can be used for coupling multiple waveguides, for example on a chip, to multiple cores in a single fiber.
Few-mode fibers are fibers having a core section in which a plurality of different modes, such as higher order modes of a fundamental mode of a light beam, may be transferred. Therefore, for certain applications the transmission properties of few-mode fibers are deemed superior to multi-core fibers. Typically, few mode fibers have a single core for transmitting the optical signals.
A multi-core fiber, for example, might not be the most optimal means for transmitting signals over long distances. This can more easily and cheaply be done by multi-mode or few-mode fibers. On the other hand, a few-mode fiber having a single optical core to transfer the different light modes cannot be easily coupled to multiple waveguides on a Silicon Photonics chip.
There is a need to provide an arrangement to optically couple multiple waveguides to a few-mode fiber, wherein light is transferred from the multiple waveguides to the few-mode fiber with low optical losses. There is also a desire to provide an arrangement to optically couple multiple waveguides to a few-mode fiber, wherein light is transferred from the few-mode fiber to the multiple waveguides with low optical losses.